Circuit interrupter



0; LE 6. FORSTESCUE.

CIRCUIT INTERRUPTER. APPLICATION FILED NOV-9. 1918- RENEWED MAR. 11,1922.

1,429,278. S Patented Sept.19,1922,

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WITNESSES: INVENTOR Patented Sept. 19, 1922.

'UNITEDSTATES 1,429,278 PATENT OFFICE.

CHARLES LE G. FORTESCUE, or PITTSBURGH, PENNSYLVANIA, ASSIGNOR 'ro WEST-INeHoUsE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION or PENN-SYLVANIA.

Application filed Novemberb, 1918, Serial No. 261,914. Renewed March 11,1922. Serial No. 543,088.

To all whom it may concern Be it known that 1, CHARLES LE G. For:-rnsoon, a subject of the Kingof Great Britain, and a resident ofPittsburgh, in the county of Allegheny and Sta'teof Pennsylvania, haveinvented a new and useful Improvement in Circuit Interrupters, of which-the following is a specification.

My invention relates to quick-acting circuit interrupter-s andparticularly to actuating electromagnets therefor.

The object of my invention is to provide an electromagnet having twomagnetic paths from one of which the flux is adapted to be deflected tothe other to obtain quick operation of an armature that shall have arelatively long range of movement. I

In co-pending application, Serial No. 258,555, filed October 17, 1918,by C. L. Fortescue and J. B. MacNeill and assigned to the WVestinghouseElectric & Mfg. Co. an electromagnet having two magnetic paths isprovided with means for deflecting the flux from one pat-h to the otherupon a sudden overload in the circuit. In order to cause the fluxdeflection to occur within a minimum period of time, with this form ofelectromagnet; the reluctance of the two paths must necessarily besubstantially the same. But, in order to obtain a relatively largemovement of the armature, it is necessary that the two paths shall be soseparated that the reluctance of one of the paths may be relativelylarge.

In view ofthe above-specified conditions, I provide an electromagnethaving two sta tionary and two movable pole pieces to constitute twomagnetic pathswhich are normally of substantially equal reluctance. Thearmature is disposed between the pole pieces and thus, when it isactuated by a spring or other energy-storing device, the movable polepieces are moved to permit the armature to have a sufiiciently greatmovement. Closed-circuit conductors are provided for damping themovement of the movable pole pieces toward thelatter part of their movement. A v

The single figure of the accompanying drawing is a diagrammatic view ofa circuit interrupter embodying my invention.

A direct-current electric circuit 1 is provided with a circuitinterrupter 2 that is actuated and controlled by an electromagneticdevice 3.

CIRCUIT INTEBRUPTER.

The device 3 comprises a magnetizable core member 4 having twostationary polar pro ect ons 5 and G and two movable polar PIOJGCtlOIlS7 and 8 that constitute two magnetic paths for the flux in the coremember 4. An armature 9 is disposed between the polar pro ecti0ns and isoperatively connected, through a rod 10, to the interrupter 2.

A spring 11 normally tends to open the interrupter, and a shunt winding12, that is connected to the circuit 1, is adapted to so energize theelectromagnet 1 as to cause the armature 9 tobridge the polarprojections 5 and and thus close the interrupter 2. Windings 13 aredisposed on the core member 4 andere so series-connected to thesecondary winding of a series transformer 14 that, when the currenttraversing the directcurrent circuit 1 changes quickly, by reason of ashort circuit or ground therein,

suflicient voltage will be induced in the secondary winding of thetransformer 141 to cause current to traverse the windings 13, the latterbeing so wound, with respect to the winding 12, that the flux whichnormally traverses the path comprising the polar projections 5 and 6 andthe armature 9 will be deflected through the polar projections 7 and 8to thus attract the armature 9 and permit the spring 11 to quickly openthe interrupter 2.

It will be understood that the two paths through the polar projectionsare normally of substantially the same reluctance, which is essential inorder to permit the quick deflection of the flux from one path to theother. However, it; is essential that the movement of the armature 9shall be such as to permit sufficient movement to actuate theinterrupter 2.

With thesmall difference in reluctance between the two paths and therelative closeness of the same to each other, it isnot possible tosecure sufiicient movement of the armature 9. In view of this, the polarprojections 7 and 8 are provided with ball bearings 15 that permit thesame to be quickly moved, under the action of the spring 11, to suchpositions as to permit the armature 9 to have the proper amount ofmovement.

7 and 8, respectively, to damp the movement thereof toward the latterpart of the armature movement.

From the foregoing, it will be seen that a very small interval o1 timeis required to Open the interrupter 2 when a fault occurs on the circuitbecause the magnetic flux is not opposed but is merely deflected fromone path to another of substantially the same reluctance, and that agreat movement of the armature is obtained after the flux has beendeflected, thereby obtaining quick operation and su'l'licient mechanicalmovement to permit efl'ective interruption of the circuit.

My invention is not limited to the particular structure illustrated, asit may be variously modified without departing from the spirit and scopeof the invention, as set forth in the appended. claims.

I claim as my invention:

1. The combination with a circuit interrupter, of an electromagnetcomprising a magnetizable core member having a pinrality of stationaryand of movable polar projections constituting two magnetic paths ofslightly different reluctance, an armature lisposed between the polarprojections and connected to the movable member of the interrupter, anda spring for so actuating the armature in one direction as to move themovable polar projections to permit relatively large movement of thearmature.

An electromagnet comprising a core member lniving two magnetic paths ofditierent reluctance, an armature tor normally completing the path ofleast reluctance, means tor deflecting the magnetic flux through theother path, under predetermined conditions, and means whereby thereluctance of the second path is adapted to be increased only after theflux is deflected.

3. An electromagnet comprising a magnetizable core member, a pluralityof stationary and of movable polar projections therefor disposedrelatively close together to constitute two magnetic paths, an armature,and means for actuating the armature in one direction and for so movingthe movable polar projections as to permit a relatively long movement orthe armature.

el. An electromagnet comprising a core member having two stationarypolar projections and two movable polar projections constituting twon'lagnet-ic paths of different reluctance. an armature, a spring foropposing the normal operation of the armature, means for so divertingthe mag netic flux through one magnetic path that the spring ispermitted to quickly actuate the armature and the' movable polarprojections, and means for damping the move ment of the polarprojections.

5. An electromagnetic device for an electric circuit comprising a coremember having two stationary polar projections and two movable polarprojections constituting two magnetic paths, an armature, means forenergizing the core member to cause the armature to bridge thestationary polar projections, and means for deflecting the flux throughthe movable polar projections to cause quick movement of the armature,under predetermined conditions.

6. An electromagnetic device for an electric circuit comprising a coremember having two stationary polar projections and two movable polarprojections constituting two magnetic paths. an armature disposedbetween the polar 'irojections, means for energizing the core member tocause the armature to bridge the stationary polar projections, meanslior so deflecting the flux that the armature bridges the movable polarprojections, means for assisting the move ment ol the armature and meansfor damping the movement of the movable polar projections.

7. An electromagnet comprising a core member having two stationary polarprojections and two movable polar projections constituting two magneticpaths, a springrestrained armature disposed normally in engagement withthe stationary polar pro jections, and means for so diverting the thisfrom the stationary polar projections that the armature shall be quicklyactuated into engagement with the movable polar projections.

8. In an electric circuit, the combination with a circuit inter-writingof an operating electromagnet therefor comprising a core member havingtwo stationary polar projections, two movable polar projections. anarmature disposed between the polar projections and o 'ierativelyconnected to the interrupter, a potential winding for so energizing thecore member that the armature is normally maintained bridging thestationary polar projections, and a current winding disposed between thestationary and the movable polar projections and energized -from thecircuit when a quick change in current obtains for so deflecting theflux through the movable polar projections that the armature quicklymoves into engagement therewith. 4 '7 9. In an electric circuit, thecombination with a circuit interrupter, of an operating electromagnettherefor comprising a core member having two'stationary polarprojections, two movable polar projections, an armature disposed betweenthe polar pro jections and operatively connected to the interrupter, apotential winding for so ener gizing the core member that the armatureis normally maintained bridging the stationary polar projections, acurrentwinding disposed between the stationary and the movable polarprojections, for deflecting the flux through the movable polarprojections to quickly move the armature into engagement therewith, andmeans for retarding the movement of the movable polar projections towardthe latter part of their movement.

10. An electromagnetic device for an electric circuit comprising a coremember having two stationary and two movable polar projectionsconstituting magnetic paths and a movable armature member, means for soenergizing the core member as. to maintain the armature in engagementwith the stationary polar projections, means for deflect ing the fluxfrom the stationary polar proje ctions to the movable polar projectionsand means for actuating the armature into engagement therewith.

11. An electromagnetic device for an electric circuit comprising a coremember having two stationary and two movable polar projectionsconstituting magnetic paths and a movable armature member, means for soenergizing the core member as to maintain the armature in engagementwith the stationary polar projections, means for deflecting the fluxfrom the stationary olar projections to the movable polar projections,means for moving the armature into engagement therewith and means fordamping the movement of the movable polar projections.

12. An electromagnetic device for an electric circuit comprising a coremember having two stationary and two movable polar projectionsconstituting magnetic paths and movable armature member, means for soenergizing the core member as to maintain the armature in engagementwith the stationary polar projections, and means for so deflecting theflux from the stationary polar projections to the movable polarprojections as to actuate the armature into engagement therewith.

13. An electromagnetic device comprising a core member having twomagnetic paths of diflerent reluctance, one path of greater reluctancecomprising two movable polar projections, an armature member, a Windingfor so energizing the core member as to maintain engagement of thearmature member with portions of the core member that comprise the pathof lesser reluctance,

and a winding disposed between the two paths for so deflecting the fluxfrom the path of less reluctance to the path comprising the movableprojections as to actuate the armature member into engagement therewith.

14:- An electromagnet comprising a core member having two magnetic pathsof different reluctance comprising two stationary and two movable polarprojections, an armature for normally completing the path of leastreluctance comprising the stationary projections, and means fordeflecting the flux through the path of the movable proj ections underpredetermined conditions, said projections co-operating to increase there- CHARLES LE G. FORTESCUE.

